Doctors believe a woman who died from rare brain-eating amoebas used tap water to rinse her sinuses.

The 69-year-old Seattle resident died in February after undergoing brain surgery at Swedish Medical Center. Her doctor tells The Seattle Times there was "amoeba all over the place just eating brain cells."

According to a study published in the International Journal of Infectious Diseases, doctors believe the woman likely became infected when she used tap water in her neti pot, a teapot-like vessel used to flush out nasal passages.

Health officials suggest using only distilled, sterile or previously boiled water to rinse sinuses. Tap water can contain tiny organisms that are safe to drink but could survive in nasal passages.